108 research outputs found

    Hominin tracks in southern Africa: a review and an approach to identification

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    Three Late Pleistocene hominin tracksites have been reported from coastal aelioanites in South Africa. Two have been dated to 124 ka and 117 ka , and the third is inferred to be 90 ka. There are no other globally reported sites for probable Homo sapiens tracks older than 46 ka. Given this documented record, a search for further hominin tracksites in southern Africa may well yield additional positive results. However, this is a field that demands scientific rigour, as false positive tracksites (pseudotracks) may occur. Criteria have been developed for the identification of fossil vertebrate tracks and hominin tracks, but these are specific neither to southern Africa nor to aeolianites.An important caveat is that the tracks of shod humans would not fulfil these criteria. Preservation of tracks varies with facies and is known to be suboptimal in aeolianites. An analysis of the tracks from the three documented South African sites, along with pseudotracks and tracks of questionable provenance, allows for the proposal and development of guidelines for fossil hominin track identification that are of specific relevance to southern Africa. Such guidelines have broader implications for understanding the constraints that track preservation and substrate have on identifying diagnostic morphological features.Palaeontological Scientific Trust (PAST)JNC201

    Adverse health effects of nighttime lighting: comments on american medical association policy statement.

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    The American Medical Association House of Delegates in June of 2012 adopted a policy statement on nighttime lighting and human health. This major policy statement summarizes the scientific evidence that nighttime electric light can disrupt circadian rhythms in humans and documents the rapidly advancing understanding from basic science of how disruption of circadian rhythmicity affects aspects of physiology with direct links to human health, such as cell cycle regulation, DNA damage response, and metabolism. The human evidence is also accumulating, with the strongest epidemiologic support for a link of circadian disruption from light at night to breast cancer. There are practical implications of the basic and epidemiologic science in the form of advancing lighting technologies that better accommodate human circadian rhythmicity

    Pre-service teachers' perceptions of technology and technology education

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    Technology teachers’ perceptions and understanding of the nature of technology heavily influences their perceptions of technology education and consequently shapes their teaching practice. Understanding the nature of technology is also an important component of technology education and in 2007 the New Zealand technology curriculum introduced a new strand called the Nature of Technology. An important part of initial teacher education programmes is therefore to help student teachers develop their concepts and philosophies of technology and technology education. This paper reports findings from a survey of New Zealand student teachers’ perceptions of technology and technology education before and after their involvement in a compulsory course in technology education. The findings reported here are some of the initial results from one institution but are part of a larger project aimed at brining together similar data from across the country to inform development of pre-service technology education programmes

    Late Pleistocene vertebrate trace fossils in the Goukamma Nature Reserve, Cape South Coast, South Africa

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    More than 100 Late Pleistocene trace fossil sites have been identified in aeolianites along a 275 kilometer stretch of the Cape south coast. A zone of concentration of such sites exists within the Goukamma Nature Reserve, both along the coast and along the Goukamma River. These sites provide insight into the Pleistocene fauna along the Cape south coast. Features include lion trackways, multiple elephant tracksites, a long trackway most likely attributable to Long-horned Buffalo, medium-sized carnivore tracks, avian tracks, equid tracks attributable to the giant Cape horse, numerous artiodactyl tracks, and burrow traces. The ephemeral nature of the tracksites makes regular surveys of these areas desirable, along with site documentation and trackway replication and preservation initiatives. The protected status of the area offers opportunities for geoheritage appreciation.JN

    Meeting Report: The Role of Environmental Lighting and Circadian Disruption in Cancer and Other Diseases

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    Light, including artificial light, has a range of effects on human physiology and behavior and can therefore alter human physiology when inappropriately timed. One example of potential light-induced disruption is the effect of light on circadian organization, including the production of several hormone rhythms. Changes in light–dark exposure (e.g., by nonday occupation or transmeridian travel) shift the timing of the circadian system such that internal rhythms can become desynchronized from both the external environment and internally with each other, impairing our ability to sleep and wake at the appropriate times and compromising physiologic and metabolic processes. Light can also have direct acute effects on neuroendocrine systems, for example, in suppressing melatonin synthesis or elevating cortisol production that may have untoward long-term consequences. For these reasons, the National Institute of Environmental Health Sciences convened a workshop of a diverse group of scientists to consider how best to conduct research on possible connections between lighting and health. According to the participants in the workshop, there are three broad areas of research effort that need to be addressed. First are the basic biophysical and molecular genetic mechanisms for phototransduction for circadian, neuroendocrine, and neurobehavioral regulation. Second are the possible physiologic consequences of disrupting these circadian regulatory processes such as on hormone production, particularly melatonin, and normal and neoplastic tissue growth dynamics. Third are effects of light-induced physiologic disruption on disease occurrence and prognosis, and how prevention and treatment could be improved by application of this knowledge

    Sistem Pengendali Kecepatan Motor Dc Pada Lift Barang Menggunakan Kontroler Pid Berbasis Atmega 2560

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    Lift barang adalah angkutan transportasi vertikal digunakan untuk memindahkan barang. Lift ini sangat khusus fungsinya untuk barang saja, lift ini hampir sama dengan lift penumpang namun ada sedikit perbedaan dalam sistem keamanannya. Lift barang yang sekarang memang sudah otomatis tetapi hanya pada gedung bertingkat tinggi. Untuk minimarket atau home industry yang memiliki struktur bangunan 2 lantai, banyak dijumpai masih menggunakan pengkatrolan secara manual oleh tenaga manusia untuk memindahkan barang. Hal ini cukup tidak efisien. Pada penelitian ini telah dirancang sistem pengaturan kecepatan motor DC pada lift barang menggunakan kontoler PID dengan kontruksi sistem yang sederhana. Digunakan Kontroler PID untuk mengurangi kesalahan, sehingga putaran motor dapat sesuai dengan kecepatan yang diinginkan. Dengan bantuan kontroler PID maka lift barang mampu bergerak dengan aman dan halus. Pada skripsi ini digunakan metode Ziegler-Nichols tunning 2. Dalam pembuatannya digunakan Arduino Mega 2560, rotary encoder Autonic E40H8 500-6-L-5, limit switch, dan motor DC. Berdasarkan data respons sistem yang diperoleh dari pengujian dengan menggunakan metode kedua Ziegler-Nichols, maka parameter kontroler PID dapat ditentukan dengan gain Kp = 7.71, Ki = 7.035 dan Kd = 2.113.Kata Kunci— Lift barang, Pengendalian Kecepatan, PID, Arduino Mega 2560

    Manus track preservation bias as a key factor for assessing trackmaker identity and quadrupedalism in basal ornithopods.

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    BACKGROUND: The Las Cerradicas site (Tithonian-Berriasian), Teruel, Spain, preserves at least seventeen dinosaur trackways, some of them formerly attributed to quadrupedal ornithopods, sauropods and theropods. The exposure of new track evidence allows a more detailed interpretation of the controversial tridactyl trackways as well as the modes of locomotion and taxonomic affinities of the trackmakers. METHODOLOGY/PRINCIPAL FINDINGS: Detailed stratigraphic analysis reveals four different levels where footprints have been preserved in different modes. Within the tridactyl trackways, manus tracks are mainly present in a specific horizon relative to surface tracks. The presence of manus tracks is interpreted as evidence of an ornithopod trackmaker. Cross-sections produced from photogrammetric digital models show different depths of the pes and manus, suggesting covariance in loading between the forelimbs and the hindlimbs. CONCLUSIONS/SIGNIFICANCE: Several features (digital pads, length/width ratio, claw marks) of some ornithopod pes tracks from Las Cerradicas are reminiscent of theropod pedal morphology. This morphological convergence, combined with the shallow nature of the manus tracks, which reduces preservation potential, opens a new window into the interpretation of these tridactyl tracks. Thus, trackmaker assignations during the Jurassic-Cretaceous interval of purported theropod trackways may potentially represent ornithopods. Moreover, the Las Cerradicas trackways are further evidence for quadrupedalism among some basal small- to medium-sized ornithopods from this time interval

    The Pleistocene fauna of the Cape south coast revealed through ichnology at two localities

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    East of Still Bay on the Cape south coast of South Africa lies a rugged, remote stretch of sea cliffs that expose Late Pleistocene aeolianites. A zone of dense concentration of fossil tracks occurs within this area. Two large rocks, which we call Roberts Rock and Megafauna Rock, were identified ~400 metres apart. These rocks contained a variety of trackways, individual tracks, burrow traces and invertebrate trace fossils on multiple bedding planes. Both rocks were found ex situ, but their context could be determined. Roberts Rock has subsequently slid into the ocean, and Megafauna Rock lies at the base of a coastal cliff. Probable trackmakers include elephant, long-horned buffalo, giant Cape horse, rhinoceros, medium and small artiodactyls, golden mole, birds and invertebrates. Dating studies at an adjacent site, which is comparable to the stratigraphy described here, indicate that both rocks were most likely deposited in Marine Isotope Stage 5e (~128–116 ka). Analysis and description of these tracksites confirms the potential of ichnology to complement the skeletal fossil record and to enhance the understanding of Pleistocene life in southern Africa. The ephemeral nature of such tracksites makes repeated visits to this coastline desirable, both to monitor the fate of known sites and to search for newly exposed trace fossil surfaces. Significance: • Roberts Rock and Megafauna Rock are two remarkable fossil tracksites on the Cape south coast, which contain tracks of four members of the Late Pleistocene megafauna. They provide a glimpse of Pleistocene dune life and suggest an area teeming with large mammals. • These tracks were made on dune surfaces near an interface between the grassland of the Palaeo-Agulhas Plain and the inland Fynbos–Strandveld–Renosterveld. Faunal assemblages from both vegetation zones might therefore be recorded. • The trace fossil record and body fossil record both have inherent biases, but have the potential to independently provide complementary information on palaeofaunal composition. • The two rocks have provided the first South African records of fossil elephant tracks (as first described by Dave Roberts and colleagues in 2008), the first rhinoceros track and the first extinct giant Cape horse track, and track evidence of the extinct long-horned buffalo. • Roberts Rock has slumped into the ocean, and it provides an example of the fate of many exposed tracksites. Conversely, new sites frequently become exposed. This scenario stresses the need for regular ichnological surveys along this track-rich coastline to monitor existing sites and to search for new sites

    Plasticity of the Intrinsic Period of the Human Circadian Timing System

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    Human expeditions to Mars will require adaptation to the 24.65-h Martian solar day-night cycle (sol), which is outside the range of entrainment of the human circadian pacemaker under lighting intensities to which astronauts are typically exposed. Failure to entrain the circadian time-keeping system to the desired rest-activity cycle disturbs sleep and impairs cognitive function. Furthermore, differences between the intrinsic circadian period and Earth's 24-h light-dark cycle underlie human circadian rhythm sleep disorders, such as advanced sleep phase disorder and non-24-hour sleep-wake disorders. Therefore, first, we tested whether exposure to a model-based lighting regimen would entrain the human circadian pacemaker at a normal phase angle to the 24.65-h Martian sol and to the 23.5-h day length often required of astronauts during short duration space exploration. Second, we tested here whether such prior entrainment to non-24-h light-dark cycles would lead to subsequent modification of the intrinsic period of the human circadian timing system. Here we show that exposure to moderately bright light (∼450 lux; ∼1.2 W/m2) for the second or first half of the scheduled wake episode is effective for entraining individuals to the 24.65-h Martian sol and a 23.5-h day length, respectively. Estimations of the circadian periods of plasma melatonin, plasma cortisol, and core body temperature rhythms collected under forced desynchrony protocols revealed that the intrinsic circadian period of the human circadian pacemaker was significantly longer following entrainment to the Martian sol as compared to following entrainment to the 23.5-h day. The latter finding of after-effects of entrainment reveals for the first time plasticity of the period of the human circadian timing system. Both findings have important implications for the treatment of circadian rhythm sleep disorders and human space exploration

    A Strong B-cell Response Is Part of the Immune Landscape in Human High-Grade Serous Ovarian Metastases

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    In high-grade serous ovarian cancer (HGSOC), higher densities of both B cells and the CD8 + T-cell infiltrate were associated with a better prognosis. However, the precise role of B cells in the antitumor response remains unknown. As peritoneal metastases are often responsible for relapse, our aim was to characterize the role of B cells in the antitumor immune response in HGSOC metastases. Unmatched pre and post-chemotherapy HGSOC metastases were studied. B-cell localization was assessed by immunostaining. Their cytokines and chemokines were measured by a multiplex assay, and their phenotype was assessed by flow cytometry. Further in vitro and in vivo assays highlighted the role of B cells and plasma cell IgGs in the development of cytotoxic responses and dendritic cell activation. B cells mainly infiltrated lymphoid structures in the stroma of HGSOC metastases. There was a strong B-cell memory response directed at a restricted repertoire of antigens and production of tumor-specific IgGs by plasma cells. These responses were enhanced by chemotherapy. Interestingly, transcript levels of CD20 correlated with markers of immune cytolytic responses and immune complexes with tumor-derived IgGs stimulated the expression of the costimulatory molecule CD86 on antigen-presenting cells. A positive role for B cells in the antitumor response was also supported by B-cell depletion in a syngeneic mouse model of peritoneal metastasis. Our data showed that B cells infiltrating HGSOC omental metastases support the development of an antitumor response. Clin Cancer Res; 1-13. ©2016 AACR
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